autofs: fix autofs_sbi() does not check super block type

autofs_sbi() does not check the superblock magic number to verify it has
been given an autofs super block.

Link: http://lkml.kernel.org/r/153475422934.17131.7563724552005298277.stgit@pluto.themaw.net
Reported-by: <syzbot+87c3c541582e56943277@syzkaller.appspotmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ian Kent 2018-08-21 21:51:45 -07:00 committed by Linus Torvalds
parent 778a33959a
commit 0633da48f0
2 changed files with 3 additions and 2 deletions

View File

@ -26,6 +26,7 @@
#include <linux/list.h>
#include <linux/completion.h>
#include <linux/file.h>
#include <linux/magic.h>
/* This is the range of ioctl() numbers we claim as ours */
#define AUTOFS_IOC_FIRST AUTOFS_IOC_READY
@ -124,7 +125,8 @@ struct autofs_sb_info {
static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb)
{
return (struct autofs_sb_info *)(sb->s_fs_info);
return sb->s_magic != AUTOFS_SUPER_MAGIC ?
NULL : (struct autofs_sb_info *)(sb->s_fs_info);
}
static inline struct autofs_info *autofs_dentry_ino(struct dentry *dentry)

View File

@ -10,7 +10,6 @@
#include <linux/seq_file.h>
#include <linux/pagemap.h>
#include <linux/parser.h>
#include <linux/magic.h>
#include "autofs_i.h"